Process of making tough styrol polymers and product



Patented Nov. 1, 1938 PROCESS OF MAKING TOUGH STYROL POLYMERS ANDPRODUCT Omar H. Smith, West Englewood, N. 1., assignor, by mesneassignments, to Carbide and Carbon Chemicals Corporation, New York, N.Y., a corporation of New York No Drawing. Application February 6, 1932,Se-

rial No. 591,453. Renewed October 24, 1936 16 Claims. (01. 260-2) Thisinvention relates to a process for making tough styrol polymers, andmore particularly to a process for making such tough polymers withimproved properties, whether the styrols used in the process areproduced by heating halogen alkyl benzols in the presence of a base orare produced by ordinary cracking methods. It further relates to theproduct obtained. a

This application is a continuation in part of my application Serial No.365,794, filed May 24, 1929, now Patent No. 1,908,549, May 9, 1933.

Styrols have been produced by various processes, and various processesare known for polymerizing such styrols, some of which latter processesproduce the tough or alpha polymer or meta styrol, while others producea brittle polymer.

However, up to the present time known practical applications of thelatter are limited as compared wtih the tough polymer. In Patent No.1,926,314, dated September 12, 1933, I have disv closed a method formaking a styrol by heating a halogen alkyl benzol in the presence of abase under atmospheric pressure. When the styrol thus formed has beenpolymerized by the methods previously used for producing a toughpolymer, it has instead produced a brittle polymer. While applicant doesnot definitely know why such styrols, produced by heating a halogenalkyl benzol in the presence of a base, form brittle polymers whenpolymerized by methods ordinarily producing a tough polymer, and he doesnot wish to be bound by any theory; he believes that possibly thisdifficulty may be caused by residual halogen.

An object of the invention is to provide a process for making a toughstyrol polymer of improved properties from an unpolymerized styrolcapable of producing a tough polymer under previously known properworking conditions. A

4 further object is to provide a process for making a tough styrolpolymer from an unpolymerized styrol which will ordinarily produce abrittle polymer under any of the previously known working conditions. Astill further object is to produce a styrol polymer of greatly improvedproperties. Other objects will appear from the detailed disclosure inthe specification and claims.

The invention consists broadly in polymerizing a styrol to a toughpolymer of improved qualities by heating the styrol in the presence of aliquid which is immiscible with the styrol and which boils at atemperature'not substantially higher than 120 C., such as water, usingas a raw material either a. styrol obtained by heating a halogen alkylbenzol in the presence of a base or a styrol obtained in the ordinarymanner by the usual cracking processes.

. When styrol, as obtained from halogen alkyl benzol by heating in thepresence of a base, has 5 been polymerized by the previously known methods for producing" a tough polymer, a brittle polymer has invariablybeenobtained instead of the expected tough polymer. But I have foundthat when the same styrol is polymerized in the 10 presence of water, atough and improved polymer is obtained when other suitable conditionsfor obtaining the tough polymer are present. In addition, I have alsofound that by heating with water a styrol obtained by the usual cracking15 processes, a" by cracking ethyl benzol, and which J would ordinarilygive a tough polymer under proper polymerizing conditions, I haveobtained a tough polymer of greatly improved characteristics.

' The following examples will illustrate the resuits obtained whencarrying out my process, us-

ing either a styrol obtained by heating a halogen alkyl benzol in thepresence of a base, or using a styrol obtained by the usual crackingprocesses, such as by cracking ethyl benzol.

Ex. 1- (blank) .-A 24 gram sample of styrol solution, obtained byheating chlor ethyl benzol at atmospheric pressure in the presence ofpyridine, was polymerized by heating for '72 hours under a refluxcondenser at a temperature between 115 and 120 0., this solution havinga concentration of about to styrol. No water was used, and 10.5 grams ofbrittle resin were obtained. T

Ex. 2'. (blank).-A gram sample of a similarly obtained styrol solutionhaving a concentration of 45% to 50% and a boiling point below 160 C.was polymerized by heating under a reflux condenser at atmosphericpressure for 136 hours at to C. The resulting resin was isolated byremoval of the volatile hydrocarbons by steam distillation, and dried inan electric oven at 60 C. No water was used during polymerization, and38 grams of brittle resin were obtained.

Er. 3.-A 28 gram sample of similarly prepared. styrol solution having aconcentration of 50% and a boiling point below C. was added 5 toapproximately 60 grams or water, and the mixture was heated for 72 hoursunder a reflux condenser while boiling the water. The resulting polymerwas isolated by removal 01. the volatile hydrocarbons by steamdistillation, and dried-55 in an electric oven at 70 C., and 11 grams.of a tough non-brittle resin were obtained.

Ex. 4.-In this example there were used 87 grams of a 52% solution ofstyrol obtained in the ordinary manner by a cracking process, the

starting material being ethyl benzol. Such styrol when polymerizedby'the usual methods used for obtaining a tough polymer would produce atough polymer. To the .87 grams of styrol solution there was added anequal amount of water and the mixture was heated under a refluxcondenser with the water boiling for 92 hours. The water was thenseparated from the mixture and the solvent removed by drying in vacuumat about 120 C. There were obtained 34 grams of tough polymerizedstyrol.

As showing the improved characteristics of the tough product obtained inExample 4 over a similar tough styrol polymerized in the absence ofwater, the material was molded and given the usual tests for breakingstrength and flexibility. It showed a transverse breaking strength, ormodulus of rupture, of 10,800 pounds per square inch and a flexibilityindex of 656. A blank from.

the same styrol which was polymerized to a tough polymer by the usualprocedure in the absence of water gave a transverse breaking strength ofonly 8000 pounds per square inch and a flexibility index of 280.

The transverse breaking strength and the flexibility index of thepolymerized styrol may be measured as follows:

A molded strip of the material is supported horizontally on two parallelknife edges 3 inches apart, to form a simple beam. It is then subiectedto an increasing load, applied by means of a third knife edge at thecenter of the beam, until the strip breaks. The breaking strength isthen readily calculated in known manner from the observed breaking load,the dimensions of the test piece, and the distance between the supports.The maximum deflection of the third knife edge (in mils) is a measure ofthe flexibility of the material being tested. For convenience, the testpiece used is strip of rectangular uniform crosssection, approximately0.09 inch by 0.5 inch by 4 inches in size. For strips having only asmall deviation in thickness, there is an approximately linear relationbetween the thickness and the reciprocal of the maximum deflection. Theterm flexibility index as used in the specification and claims expressesthe calculated maximum deflection, in mils, of a uniform rectangularstrip 0.09 inch in thickness supported by two knife edges 3 inchesapart, as described above.

By previously known methods of polymerizing styrol, it has been possibleto obtain styrol polymers having a maximum breaking strength of onlyabout 8000 pounds per square inch and a flexibility index of only about300. By the proces of the present invention styrol polymers may beproduced which are characterized by breaking strength .substantially inexcess of 9000 pounds per square inch and a flexibility indexsubstantially in excess of 300. Usually these products have a transversebreaking strength of from 10,000 to 16,000 pounds per square inch and aflexibility index of from 400 to 1000.

Ex. 5.-In this example a 60% solution of styrol (500 grams), as obtainedby crackingethyl benzol, was mixed with 250 grams of water, and themixture heated for 96 hours with the water boiling. The meta styrol wasisolated as before and a slab molded from it. The transverse breakistrength was 15,200 pounds per square inch, and the flexibility indexwas 900. v

' In carrying out the process the styrol solution used should have aconcentration of approximately 40% to 90%. The temperature of thestyrol-water mixture may be maintained at less than 100 C., and improvedresults still obtained; However, best results have been obtained whensuflicient heat is applied to boil the water fairly vigorously, so as toobtain an eflicient intermingling of the two immiscible liquid phases.

While the water may have other beneficial efiects', it is believed thatone important advantage in its use is that the water serves as anabsorber of the heat evolved during the polymerization, which is anexothermic reaction, thus providing eflicient control of the temperatureof the reaction mixture. The steam formed when the water is boiledvigorously also serves to displace the air above the liquid mixture fromthe containing vessel and to prevent access of oxygen to the reactionmixture. Equivalent liquids may be substituted for water in thisprocess. The use of an efficient reflux condenser is desirable.

While the water used may be as low as 5% of the weight of the styrolsolution, it is preferred to use from about to about 100% by weight ofwater. 1

In general, the time required for carrying out the polymerization variesfrom approximately 70 to 150 hours, depending on the styrolconcentration, the temperature, and other variables.

The process is also applicable to the polymerization of homologues ofstyrol, such as meta ethyl styrol, meta Z-methyl styrol, and the like,described in patent to Ostromislensky No. 1,683,402, granted September4, 1928.

From the above, it will be seen that even in the case of styrol, such asthat obtained by cracking ethyl benzol, which will give a tough polymerwhen polymerized by the usual methods, a greatly improved result hasbeen obtained by the present process of polymerizing in the presence ofwater.

At the same time, the process enables a tough polymer to be obtainedfrom a styrol derived from a halogen alkyl benzol. which ordinarilywould give a brittle polymer if polymerized by the usual method employedfor obtaining a tough polymer.

The process is simple and in addition to the advantages above set forth,it gives a good yield of the polymer. process have been given asillustrations, it is obvious that changes may be made in its detailswithout departing from the scope of the invention as deflned by theappended claims.

I claim:

1. The procas of producing a tough alpha meta styrol of increasedstrength and flexibility,

which comprises adding water to a solution of a While specific examplesof the 1 tinuous intermingling of the two immiscible liquid phases byheating, and continuing said heating until a tough styrol polymer isproduced.

. in an amount not less than 5% by weight of said solution, eflecting anintimate and continuous intermingling of the two immiscible liquidphases by heating, and continuing said heating imtil a tough styrolpolymer is produced.

.4. The process of producing a tough alpha meta styrol of increasedstrength and flexibility, which comprises adding water to a solution ofa styrol of approximately 40 to 90% concentra tion, in an amount notless than 5% by weight of said solution, eflecting an intimate andcontinuous intermingling of the two immiscible liquid phases by heatingto not tially less than the boiling point of the water, and continuingsaid heating for approximately l to 150 hours to produce a tough styrolpolymer. 1

5. The process of polymerizing a styrol to produce a tough alpha polymerof increased strength and flexibility, which comprises adding water toa. styroi solution of above 40% concentration, in an amount not lessthan 5% by weight of said solution, effecting an intimate and continuousintermingling of the two immiscible liquid phases by heating at notsubstantially below 100 0., and continuing said heating until a. toughstyrol polymer is produced.

6. The process of polymerizing a styrol to produce a tough alpha polymerwhich comprises adding water to a styrol solution of not substantiallyless than concentration, in an amount not less than 5% by weight of saidsolution, effecting an intimate and continuous intermingling of. the twoimmiscible liquid phases by heating at the boiling point of the waterand at approximately atmospheric pressure, and continuing said heatingfor substantially 92 hours to produce a tough styrol polymer, separatingout the water, and removing solvent by drying in vacuum above theboiling point of water.

-7. 'I'heprocess of polymerizingastyroltoproduce a tough alpha polymer,which comprises adding water to a styrol, derived from a halogen alkylbenzol, in a solution of not substantially less than 40% styrolconcentration, the water being not less than 5% by weight or the styrolsolution, eiiecting an intimate and continuous intermingling of the twoimmiscible liquid phase by heating at not substantially less than 100'0. and at atmospheric pressure, and continuing said heating imtil atough styrol polymer is produced.

8. The process or polymerizing a styrol to produce a tough alphapolymer, which comprises adding water to a styrol solution of notsubstantially less than 40% concentration in an amount not less than 5%by weight of said solution, and heating under a reflux condenser tovigorously reflux the mixture until a tough styrol.

oiymerisproduced.

9. Theprocessotpolymerlsingastyroltoll'oduce a tough alpha polymer,which comprises vigorously refluxing a mixture of added water and astyrol solution of approximately 40% to 90% concentration imtil a toughstyrol polymer is produced, the water being not less than 5% by weightoi! the styrol solution.

10. The process of polymerizing 'a styrol to produce a tough alphapolymer, which comprises vigorously refluxing a mixture of added waterand a styrol solution of approximately 40% to 90% concentration forapproximately to 150 hours, the water being not less than 5% by weightof the styrol solution.

11. The process of polymerizing styrol to a; tough alpha polymer. whichcomprisesadding to a styrol solution,- of not substantially less than40% concentration, not less than 5% by weight of water based on thestyrol solution, refluxing vigorously for not less than approximately'10 hours and until a tough polymer is produced, and removing water andsolvent.

12. The process of polymerizing styrol to a tough alpha polymer, whichcomprises adding to a styrol solution, of approximately 40% toconcentration, not less than 10% by weight of water based on the styrolsolution, heating to boiling under a reflux condenser for approximately'10 to 150 hours to produce a tough styrol polymer, and removing waterand solvent.

13. 'lheprocessotpolymerlzingastyroltoproduce a. tough alpha polymer,which comprises heating the styrol in a solution of not overapproximately 90% concentration and at below approximately 120 C.,removing heat caused by the exothermic polymerizing reaction by directcontact of the solution with water during polymerizing in an amount notless than 5% by weight of the solution, and continuim saidheatinguntilatoughstyrolpolymerisproduced.

14.A tomb. strong andflexible styrol resin having a breaking strengthnot substantially less than 12,000 polmds per square inch, said resinbeing substantially identical with theproductformedbytheprocessotclaim1.

15. A tough, strong and flexible styrol rmln having a flexibility indexnot substantially less than600.saldresinbeingsubstanflallyidentical withthe product formed by polymerizing a styrol in a solution of not over90% concentration at atmospheric pressure in mechanical admixturewlthabodyotwaternot lesthan5% byweight of the styrol solution, and at atemperahire of to C.

16. A tough. strong and flexible styrol resinhavingaflexibilityindexinexcessof900,said resin being substantiallyidentical with the product formed by polymerizing a styrol in a solutionof not less than 40% concentration at atmosphericpressureinmechanicaladmixturewlth abodyot waternotlessthan5%byweightofthestyrolfl solution, and at a temperature of 100 to 120 C.

omnsm'rn.

